1. Field of Invention
This invention relates generally to apparatus for controlling the operation of a stop sign on a school bus, and more particularly to a control apparatus which when the door of the bus is opened to unload or load passengers, this causes the stop sign to swing out to an outstretched position to provide a signal alerting nearby vehicles, and which when the bus door is closed, then causes the sign to return to its retracted position.
2. Status of Prior Art
School buses pick up or discharge children attending a school serviced by the bus at various points along a route running through the community in which the school is situated. As a safety measure, school buses have for many years been equipped with a stop sign mechanism under the control of the bus driver, the mechanism acting to swing out the stop sign from its normally retracted position against the side of the bus to an outstretched position to provide a signal alerting drivers of nearby vehicles that children are entering or alighting the bus.
U.S. Pat. Nos. 2,384,689 and 3,094,683 are illustrative of manually-operated school bus sign devices, while U.S. Pat. No. 2,252,529 discloses a hydraulically-operated school bus sign.
It is also known to provide motor-operated school bus signs, such apparatus being illustrated in U.S. Pat. Nos. 2,281,717 and 4,138,668. Of greatest prior art interest in this regard is the 1982 U.S. Pat. No. 4,339,744 to Latta, Jr. In this patent, the stop sign mounted on the side of the bus is operated by an unidirectional DC motor and a linkage associated with the sign. This linkage in conjunction with limit switches acts to deploy and retract the stop sign.
The control apparatus disclosed in the Latta et al. patent is operated by the driver by means of a switch having a "deploy" and a "retract" position. The arrangement is such that when the driver sets the switch to its "deploy" position, this also acts to actuate sign lights and bus lights to cause them to flash. These flashing light signals in combination with the outstretched stop sign warn nearby cars that the door of the school bus is then open and children are being loaded or unloaded.
One practical drawback of the Latta et al. stop sign control apparatus is that it is driver operated. Should the bus driver, as sometimes occurs, fail to operate the stop sign switch before opening the door, no warning signal will then be given to alert nearby car drivers. A school bus driver's job is made difficult by the fact that his young passengers are not always well behaved; for school children are often noisy and hyperactive. Hence the conditions which prevail in a bus may distract a bus driver and induce him to forget to operate the stop sign.
Another practical drawback of the Latta et al. stop sign is that it can be damaged or rendered inoperative if the outstretched stop sign is not made to retract by the motor linked thereto but is forced to retract either accidentally or deliberately while the motor is cut off. This action may break the linkage between the stop sign and the motor.